Filter



FIG. 1 is a front perspective view of a filter;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a side view thereof;

FIG. 5 is an opposite side view thereof;

FIG. 6 is a top view thereof;

FIG. 7 is a bottom view thereof; and,

FIG. 8 is a bottom perspective view thereof.

The broken lines in the drawings illustrate portions of the filter that form no part of the claimed design. 

CLAIM The ornamental design for a filter, as shown and described. 